Tag: maths

Questions Related to maths

In a group of children $35$ play football out of which $20$ play football only, $22$ play hockey; $25$ play cricket out of which $11$ play cricket only. Out of these $7$ play cricket and football but not hockey, $3$ play football and hockey but not cricket and $12$ play football and cricket both. How many play all three games?

  1. $5$

  2. $2$

  3. $12$

  4. $60$


Correct Option: A
Explanation:

Let $F,H$ and $C$ denote the no. of children who play Football, Hockey and Cricket respectively.
Given $n(F)=35,n(H)=22,n(C)=25$ and $n(F\cap C\cap H^{\prime})=7,n(F\cap H\cap C^{\prime})=3,n(F\cap C)=12$
but $n(F\cap C\cap H^{\prime})=n(F\cap C)-n(F\cap C\cap H)$
$\Rightarrow 7=12-n(F\cap C\cap H)$
$\Rightarrow n(F\cap C\cap H)=5$
$\therefore$ No of children who play all three games is $5$
Hence, option A

If $A, {A} _{1}, {A} _{2}, {A} _{3}$ be the area of the in-circle and ex-circles, then $\dfrac {1}{\sqrt {{A} _{1}}}+\dfrac {1}{\sqrt {{A} _{2}}}+\dfrac {1}{\sqrt {{A} _{3}}}$ is equal to

  1. $\dfrac {1}{\sqrt {{A}}}$

  2. $\dfrac {2}{\sqrt {{A}}}$

  3. $\dfrac {3}{\sqrt {{A}}}$

  4. $None$


Correct Option: A
Explanation:

$A _1={\pi}{r _1}^{2}=\dfrac{{\pi}{\Delta^{2}}}{(s-a)^{2}}$

$A _2={\pi}{r _2}^{2}=\dfrac{{\pi}{\Delta^{2}}}{(s-b)^{2}}$
$A _3={\pi}{r _3}^{2}=\dfrac{{\pi}{\Delta^{2}}}{(s-c)^{2}}$
$A={\pi}{r}^{2}=\dfrac{{\pi}{\Delta^{2}}}{(s)^{2}}$
$\dfrac{1}{\sqrt{A _1}}+\dfrac{1}{\sqrt{A _2}}+\dfrac{1}{\sqrt{A _3}}=\dfrac{1}{\sqrt{\pi}}\bigg[\dfrac{s-a}{\Delta}+\dfrac{s-b}{\Delta}+\dfrac{s-c}{\Delta}\bigg]=\dfrac{1}{\sqrt{\pi}\Delta}[3{s}-(a+b+c)]=\dfrac{s}{\sqrt{\pi}\Delta}=\dfrac{1}{\sqrt{A}}$

(?)$-19657-33994=9999$

  1. $63650$

  2. $53760$

  3. $59640$

  4. $61560$

  5. None of these


Correct Option: A
Explanation:

Let $x-53651=9999$
Then, $x=9999+53651=63650$

Perform the indicated operations:
$+7(-2)+(-8)+(+3)=$

  1. -17

  2. -18

  3. -19

  4. -20


Correct Option: C
Explanation:

The value of $+7(-2)+(-8)+(+3) $

$= -14-8+3 $
$= -19$

The algebraic expression for the statement: 'Product of x and a are subtracted from the product of b and y'.

  1. ax - by

  2. x + a - by

  3. by - ax

  4. xa - b - y


Correct Option: C
Explanation:

Product of x and a = xa

product of b and y = by
On subtraction: by-ax

(?)$+3699+1985-2047=31111$

  1. $34748$

  2. $27474$

  3. $30154$

  4. $27574$


Correct Option: B
Explanation:

$x+3699+1985-2047=31111$
$\Rightarrow$ $x+3699+1985=31111+2047$
$\Rightarrow$ $x+5684=33158$
$\Rightarrow$ $x=33158-5684=27474$

$(4300731)-$? $=2535618$

  1. $1865113$

  2. $1775123$

  3. $1765113$

  4. $1675123$

  5. None of these


Correct Option: C
Explanation:

Let $4300731-x=2535618$
Then, $x=4300731-2535618=1765113$

Subtract $347657$ by $238294$ using vinculum numbers.

  1. $109363$

  2. $100363$

  3. $109373$

  4. $109563$


Correct Option: A
Explanation:

1) The first thing we do is write these numbers one on top of the other.

347657
238294

2) Now we just start subtracting vertically, and whenever our number is negative we represent it as a vinculum number.

347657
238294

3) This next subtraction is 7 – 8 = -1…so we just write this as 1 and continue on.

347657
238294
1 1 443

4) The ‘1‘ and ‘4‘ here are considered as two separate groups (since theres a non-vinculum number in-between them), so each is subtracted from 10. This has the effect of reducing the “previous one” by one.

109363

In $32$ Ekanyunena Purvena of the digit $2$ is?

  1. $13$

  2. $12$

  3. $22$

  4. $10$


Correct Option: C

In $19$ Ekadhikena Purvena of digit $1$ is

  1. $120$

  2. $119$

  3. $20$

  4. $118$


Correct Option: B